As an existing air-conditioning apparatus, there is an air-conditioning apparatus in which, for example, a compressor, a four-way valve, an outdoor heat exchanger, an electric expansion valve, and an indoor heat exchanger are connected in this order, and which is configured to be able to operate reversibly in a cooling cycle or a heating cycle by switching the four-way valve (e.g., see Patent Literature 1). When frost occurs on the outdoor heat exchanger during a heating operation, switching is performed from the heating cycle to the cooling cycle, a high-temperature and high-pressure gas refrigerant is supplied from the compressor to the outdoor heat exchanger and a reverse defrost operation is performed.